I do believe you about the K-5 even though I own a K20D. Having that much DR and ISO is game changing and would open up many opportunities. That being said...
Here is a Sears (Ricoh) 50mm f/1.7 and K10D hand held. I don't know the aperture as the lens does not report it. Its a fully manual lens. I have to focus it and set EV level. However the pic is using SR and handheld. This is with the K10D or really Samsung GX10. That sensor had really good pixel sharpness. Moreover the jpeg engine in the Samsung was for 100% sure different than the Pentax SilkyPix engine. Even the supplied RAW converter for the GX10 is not Silkypix.
Here is the front of a church hand-held...
Here is a 100% crop. The detail is pretty darn good for a lens I paid $13 for. The reason 100% detail is good is partly the lens. This is only 10mp versus the K20D 14,6 or K-5 16.3mp. But it still shows good detail why? Its ISO 100!
If you really look at your example you can see that small details have been smoothed over by the K-5 noise reduction. Its great noise reduction because a casual glance would not notice. But think about how much more detail should be in the cement of the Bridge in the crop. Or how much detail is missing in the crop.
This is why really one would ask for a static scene why not use a lower ISO. Even the mighty K-5 will smooth detail at high ISO. Just at normal viewing size you don't see it. Believe me its superb and I would benefit from it. But just speaking of this scene... Very nice picture.